Stable mirror mount assembly for an optical scanning system

Abstract

A mirror mounting structure with low thermal drift is enabled by providing a mirror mounting structure which vertically and/or horizontally aligns the mirror by providing two point forces against the mirror holding structure. The mirror holding arm is connected to a thick more rigid arm by resilient narrow slightly flexible neck portion. Screws threaded through the large arm contact alignment points on the mirror mount portion and permit accurate alignment in a desired plane. Thermal drift and hysteresis is minimized, since the alignment forces are acting upon the mirror mount portion in the same direction and minimize the deviations caused by thermal expansion.

I claim: 
     
       1. A mirror mounting assembly for maintaining a mirror in a specified vertical alignment position including, in combination, an integral mounting structure having a base portion, a first relatively thick arm portion extending vertically upward from said base portion, a mirror mount portion adapted to hold a mirror in a fixed vertical position, said mirror mount portion integrally connected to said arm portion by a narrow, slightly flexible, neck portion extending generally in a horizontal direction from said arm portion, and   biasing means secured and said arm portion and contacting the surface of said mirror mount portion at two or more points to apply an outward bias against the mirror mount portion, whereby said mirror is held in an accurate alignment during system thermal drift conditions.   
     
     
       2. The assembly of claim 1 wherein said arm portion has two threaded apertures extending therethrough in vertical alignment with each other, said biasing means comprising two screws adapted to be threaded through said apertures so as to contact the surface of said mirror mount portion at two or more vertically separated points, thereby applying a pushing force against said points. 
     
     
       3. In a laser printing system having means for generating a beam of high intensity light, a recording medium sensitive to said high intensity light, optical means comprising a plurality of optical elements including at least one mirror interposed between said light generating and said recording medium for imaging said beam to a spot at the surface of said medium, modulating means located between said light generating means and a scanner device for modulating the light beam in accordance with the information content of electrical signals, said scanner device comprising a multi-faceted polygon located in the path of said modulated beam between said beam generating means and said recording medium and having reflective facets for reflecting the beam incident thereon onto said medium, means for rotating said polygon such that the reflected light is scanned in successive traces across said medium, the improvement whereby at least one of said mirrors is located on a stable, thermal resistant mounting which includes in combination, an integral mounting structure having a base portion, a first relatively thick arm portion extending vertically upward from said base portion, a mirror mount portion adapted to hold a mirror in a fixed vertical position, said mirror portion integrally connected to said arm portion by a narrow, slightly flexible, neck portion extending generally in a horizontal direction from said arm portion, and   biasing means secured in said arm portion and contacting the surface of said mirror mount portion at two or more points to apply an outward bias against the mirror mount portion, whereby said mirror is held in an accurate alignment during system thermal drift conditions.